The danger of fire at sea is very real, and very many design concepts are intended to minimize this, and very many steps are taken to avoid this. The engine and its fuel supply are, of course, the elements on a modern power boat that are the greatest fire hazard, because of the heat generated by the engine, and the combustable fuel. They are almost always contained in an engine compartment, box, or cover, to protect boaters.
Other steps must be taken for safety. The engine box or compartment must be cleared of any possible vapors before the engine is started, and all hands must be standing by until the engine is running smoothly. Serviceable fire extinguishers must be in place at all times near the engine compartment, which is one of several safety requirements.
However, it is still possible for the engine to overheat. This may be caused by a clogged or inadequate cooling system; exceptionally hot weather; malfunction or overload of the engine; or just poor design. Such overheating can start fires in the confined engine compartment, which may spread to the rest of the ship if not contained. Leaks or breaks in the fuel supply are even more serious, and add to the hazard.
All engine compartments must be provided with a lid or lids to have access to the engine and all of its components for servicing or replacement. However, this is, normally, the only access to the engine. In the event of a fire in the engine compartment, it is suddenly necessary to find and actuate the nearest fire extinguisher, and to open the large lid to spray its special chemicals onto the burning components of the engine and its housing.
Such fires are inevitably fed by engine fuel or lubricating oil, which are extremely volatile and dangerous. The only thing that contains the fire, momentarily, is the lack of oxygen. However, the necessary opening of the lid to discover the fire, and the inevitible flooding of air and oxygen into the enclosure tends to flare-up the fire instantly and often to an extent that makes a standard fire extinguisher almost ineffective, even if the operator can survive the heat and fire of the flareup.
It is at this moment of flare-up that the fire can spread to other parts of the boat, and can, surprisingly quickly, destroy it. The mandatory life preservers on board will save the passengers--although they may be burned--but cannot be of any help to the boat.